I recently bought a 2005 Volvo V50 1.8 petrol. Done some jobs to the car and have been driving trouble free for the past 10,000km until last week when driving on the motorway. I noticed the car losing power so I pulled off the motorway and the engine was shaking and misfiring when idle. When I took off again it struggled for power. After initially googling I figured this must be either bad spark plugs or a coil pack.
Took it to my mechanic, changed the plugs and tested each coil with number 1 failing. So changed the first coil also figuring this was the issue. Started car back up. Same issue persisting. Engine shaking, rocking. Took back out the first coil and the second and done a compression test. First coil failed to make up to 60 while the second was over 160 compression.
Any ideas what this could be? Mechanic mentioned a valve might be gone which means taking the head off the engine. Expensive job either way. Is the car worth fixing? Anyone else had something similar happen to a V50 petrol. I've done a lot of maintenance work to get it road worthy with regards to brakes, suspension etc.. I really don't want to have to scrap the car after a measly 10,000km Any feedback or advice appreciated.

 

If it was really a bad coil, you pumped lots of unburned gasoline through that cylinder. That can have an effect, but it should clear up after replacing the bad coil (and after the raw gas is no longer washing the oil off the cylinder bore). Your mechanic should know this (hate to think he might be looking for an easy, expensive "fix"). Once it's no longer misfiring, just drive it for a while and see it gets better (or not).

 

you can drop a couple of tablespoons of motor oil into the spark plug hole then redo the compression test (aka a wet test). This will tell you if there is a ring problem or valves. this will also address the noted dry cylinder wall issue...